Introduction to Mid-Ocean Ridges:

Video Questions:

1: Who is NOAA? The NOAA is the National Oceanic Atmosphere Administration

2: What is the mid-ocean ridge system? What happens there? A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.

3: How long/wide the is mid-ocean ridge system? Where is it located?Making the mid-oceanic ridge system the longest mountain range in the world, with a total length of about 60,000 km.4: What type of plate boundary forms a mid-ocean ridge system? Explain. There are three types of plate boundaries: -Divergent--plates move away from each other -Convergent -- plates move toward each other -Transform -- plates slide past each otherPlates move through the process of convection in the mantle. 5: Explain how ridges form:Ridges within the ocean floor are caused by a number of underwater activities. This includes movement and shifting of tectonic plates, gushes of magma due to the pressure underneath (the magma cools beneath the ocean forming ridges), symmetrical rock formation and from the deep sea trenches that form as a result of the shift of the continental plates. That is how ridges form underwater.6: What forms most of the ocean crust? Granite and Basalt is formed mostly in the ocean's crust

7: How does hot lava respond to cold sea water? (Pillow Basalt) When hot lava meets the cooler temperatures of the ocean, an instantaneous cooling reaction takes place within the hot lava causing the minerals to form and crystallize quickly, usually of a different chemical and molecular composition if it were allowed to cool gradually at the earth's surface.

8: What is happening at the Juan de Fuca Ridge? Stretching 300 miles along the coast of Washington and Oregon, the Juan de Fuca Ridge is an underwater volcanic mountain range. Created by the separation of the Juan de Fuca Plate and the Pacific Plate, the Juan de Fuca Ridge is home to an extraordinary community of life whose source of energy is not the sun, but sulfur-rich chemicals. Undersea springs called hydrothermal vents release scalding plumes of 400°F lava-heated water carrying sulfur-bearing minerals. The plumes look like black clouds and the vents are thus named “black smokers.” On contact with frigid seawater, the minerals crystallize and settle on the seafloor around the vent openings. Over time, the mineral deposits grow like chimneys to heights of a hundred feet or more.9: What does the rate of spreading dictate?The rate of spreading indicates by influences/persuades the topography of the ridge.

10: How hot can sea water be heated to at the mid-oceanic ridges? Along the crests of the volcanoes of the mid-ocean ridge, cracks allow the near-freezing sea water to seep deep into the hot new crust. This water becomes superheated to temperatures of greater than 400ºC (752 ºF), causing the water to become so buoyant it shoots out of the seafloor at very high speeds, like water gushing from a broken fire hydrant.

11: Explain how HYDROTHERMAL Vents are formed: Hydrothermal vents are essentially underwater geysers created bytectonic plates. These huge plates in the Earth’s crust move and create cracks in the ocean floor. Ocean water enters the cracks, is heated up by the Earth’s magma, and then released through the hydrothermal vents, along with minerals such as hydrogen sulfide, which end up forming volcano-like projections on the seafloor.

12: Why is the hot mineral water so important? What do they support? The super heated water dissolves minerals and carries them out to the surface and nourishes the animals and plants.13: What is chemosynthesis? How does it differ from photosynthesis? Chemosynthesis is the use of energy released by inorganic chemical reactions to produce food. Chemosynthesis is at the heart of deep-sea communities, sustaining life in absolute darkness, where sunlight does not penetrate. On the other hand, Photosynthesis occurs in plants and some bacteria, wherever there is sufficient sunlight – on land, in shallow water, even inside and below clear ice.